Proteins from Drosophila melanogaster nuclei which are soluble in 2% trichloroacetic acid (HMG-like proteins) will be identified and characterized with respect to molecular weight, isoelectric point, and elution from the cation exchange resin Bio-Rex 70. Amino acid analysis will be performed on the two major proteins. Micrococcal nuclease or DNAse II fragmented chromatin will be fractionated by 0.1 M NaCl or 2mM MgCl2 precipitation, respectively. The presence or absence of the HmG-like proteins will be determined for each fraction by electrophoresis, and the effectiveness of each procedure for the fractionation of Drosophila active gene sequences will be determined by DNA-RNA hybridization with poly-A containing cytoplasmic RNA. Antisera will be made to the purified HMG-like proteins and used to determine their chromosomal location on salivary gland polytene chromosomes by indirect immunofluorescent staining.